This proposal requests funds for an international conference on the biology of hematopoiesis. The Symposium will comprehensively review recent developments at the cellular and molecular levels in the field of hematopoietic stem cell differentiation and growth. Our specific aim is to gather and attract a group of over 200 scientists who are of international repute or who are in the formative years of their careers as scientists in the field for the purpose of presenting, discussing and exchanging scientific information relative to hematopoietic stem cells. Our goal is to encourage the free exchange of conceptual and technical information regarding newly developed cell culture, biochemical, and molecular genetic techniques. Our hope is that potentially fertile areas of basic and clinical research may be identified in order to accelerate the application of laboratory findings to the bedside as it relates to derangements of hematopoiesis. The proceedings of this conference will be published in a timely fashion with the hope of stimulating continued development of this field. The symposium will provide a multidisciplinary approach to the field of hematopoiesis. It is scheduled to take place over a full five-day period and to address the following areas: (1) tissue culture systems and cellular requirements for hematopoietic differentiation; (2) growth factor receptors and molecular and cell biology of hematopoiesis, including cell surface receptors for growth factors, post-receptor events and DNA structural modifications during differentiation; (3) gene therapy, including regulation of gene expression, gene transfer, in vivo models of gene therapy and the future of human gene therapy; (4) hematopoietic growth factors, including recombinant and naturally occurring, endogenous growth factors; and (5) radiation injury to bone marrow stem cells and in vivo effects of purified hematopoietic growth factors. In addition to workshops, poster sessions will provide the opportunity for young investigators to present data pertaining to each of these topics. Our longterm objective is to review and explore new approaches to understanding the cell biology of hematopoiesis.